A three-dimensional imaging system for obtaining a three-dimensional image of an object being scanned ultrasonically comprises a source arrangement for sequentially transmitting ultrasonic energy toward the object in successive directions in a first scanning plane, followed by sequential transmission of ultrasonic energy toward the object in successive directions in successive scanning planes, a detector arrangement for receiving reflected energy and converting the reflected energy to electrical signals, and a processor for processing the electrical signals to develop reconstructed image data of the object, the reconstructed image data comprising forward projections of the object into a left image plane and a right image plane to form left and right images, respectively, the left and right images forming a stereo pair for composite display by a display unit. In one embodiment, each successive scanning plane is parallel to the first scanning plane. In a further embodiment, successive scanning planes have increasing angular orientations, measured at the point of ultrasonic transmission, with respect to the first scanning plane. In another embodiment, successive scanning planes have increasing angular orientations, measured along a common axis, with respect to the first scanning plane.